Sulfur-dioxide modified tetrafluoroethylene polymer



, Patented Nov. 26, 1 V I 1 SULFUR-DIOXIDE MODIFTED 'ra'rm- FLUOROETHYLENE POLYMER Jesse Harmon and Robert M. Joyce, Jr., Wilmington, Del., assig'nors to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware v I Y No "Drawing.

1. This invention relates to'polymeric materials and more particularly to sulfur dioxide-modified tetrafluoroethylene polymers.

Polytetrafluoroethylene is a hard, tough, in-= fusible solid which is insoluble in and'unattacked 5 polymers of this invention are macromolecular by inorganic acids, alkalies and organic solvents. polymers having the empirical formula While this combination of propertiesis very desirable for a great many applications, many of these properties make the polymer unsuitable for wherein Z and are integers, the ratio of to being within the range of from 1:1 to 125:1;

s invention has as an'object new and useful Those of greatest utility have the empirical forcomPOsitlonS of matter- A further object is the mula (CzFt) e.(S02) as hereinbefore defined, in preparation of sulfur dioxide-modified 'tetrafluwhich the ratio of x to y is within the range or oroethylene polymers. A still further object refrom 6:1 to 125:1. sides m the sulfur dioxide-modified polymers The ratio of S0: to C2F4 in the polymers of this which 9 characterized by lower menu? invention may be varied within the above limits and improved workability. Additional ob ects will by varying the m ratio of Sulfur dioxide to tetrag become apparent from an examination of the folfiuomethylehe in the reaction mixture Thus lowing descnption and claims said ratio in the reaction mixture may be varied These and 0th! objects and advantages are widely; although usually the mol ratio of sulfur accomplished according to the herein described dioxide to tetrafi or thylene m the reaction mvenuon which comprises polymerizing tetra mixture is within the range of from 1:10 to 10:1. fiuoroethylene in the presence of sulfur dioxide The catalysts used in the practice this under substantially anhydrous conditions and in Vehtion are organicheroxy compounds g" thhse the absence of diluents using an organic peroxy .5 organic compounds which contain compound as catalyst as more fully described structura Examples thesev compounds heremafter' diacyl peroxides, such as benzoyl peroxide, di- J The followmg example in P m 'F lauroyl peroxide; dialkyl' peroxides, such as diare in Parts by Weight unless Otherwlse weaned, ethyl peroxide, di(tert. butyDperoxide; and alkyl is given for illustrative purposes and is not inhydropemxides, such as tam hutylhydmpemxidep tended any restrictions herein Appreciable efiects are had when the amount of described Y catalyst employed is as low as 0.001% and when Example it is as high as 5% ofthe sum of the weights of l the sulfur dioxide and tetrafluoroethylene in the A silver-lined shaker tube was swept with nitroreaction mixture. The use of amounts of catalyst gen and. charged with one part of benzoyl perlower than 0.001% and higher than 5% is not oxide. The head was fastened to the tube and recommended for economic reasons since inferior the tube was evacuated and charged with 128 results are obtained when the catalyst is emparts of sulfur dioxide and 50 parts of tetraplOyed outside the indicated range. Optimum fluoroethylene through a valve. Thevalve was 40 results are obtained when the amount of catalyst closed and the tube was shaken first at room tememployed is within the range of from 0.01% to 1%. perature for three hours and then for four hours based upon the total weight of the sulfur dioxide at 80 C. The tube was then cooled and the and tetrafiuoroethylene in the reaction mixture. unreacted sulfur dioxide and tetrafiuoroethylene The process of this invention .can be carried were removed by releasing the pressure. The out at atemperature within the range of from product consisted of 21 parts of a hard, brittle, 0 C. to 200 C. The reaction is generallycarried tan-colored solid. The product when fused was out within the range offrom 25 C. to 150 C. a mobile liquid, whereas unmodified polytetra- The polymerization is carried out under superfluoroethylene retained its form when heated at atmospheric pressure, generally 'autogenous prestemperatures as high as 400 C. The sulfur disure, and usually within the range'of from three oxide-modified tetrafluoroethylene polymer was atmospheres up to'1000'atmospheres. The maxinon-flammable, melted at 310 C., was insoluble mum possible pressure apparently is limitedonly in water, dioxane, acetic acid, ethanol, xylene and by the apparatus available. acetone. It was unaffected by hot dilute alkali The products of this'invention'are characterized'by improved workability and lower softening or acid but was darkened by hot concentrated Application September 21-, 1945, Serial No. 617,930

. 4 Claims. (.01. 260-801]- sulfuric acid. It contained 0.47% sulfur, or an average ratio of one sulfur dioxide unit to 67.4 tetrafluoroethylene units.

The sulfur dioxide-modified tetrafluoroethylene temperatures compared to those of unmodifl tetrafiuoroethyiene polymers. They may be used as molding plastics, fllms,flbers and adhesives and as electrical insulation.

As manyapparently widely diiferent embodiments of this invention'may be made without de-, parting from the spirit and scope thereof, it is to be understood that we do not limit ourselves to the specific embodiments thereof except-as defined in the appended claims.

Having described the present invention,. the

following is claimed as new and useful:

1. A macromolecular polymer having the empirical formula (CaF4)=.(SO:') y, wherein wand 11 are integers, the ratio of xto 14 being within the range of from 1:1 to 125:1.- v g the moi ratio of sulfur dioxide to tetrafiuoro- 1s ethylene'belng within the range of from 1:10 to v 2. A macromolecular polymer having the empirical formula (C2F4)=.(SO2)y, wherein a: and y are integers, the ratio of :c to 1/ being within the range of from 6:1 to 125:1.

3. The process for obtaining a sulfur dioxide- 4. The process for obtaining modified tetrafluoroethylene polymer which com- 4 modified tetraiiuoroethylene polymer which comprises subjecting to superatmospheric pressure 'and a temperature within the range of from 0 C.to 200 C. a mixture consisting of sulfur dioxide, tetrafluoroethylene and as catalyst an organic peroxy compound.

prises subjecting-to a pressure within the range of from three atmospheres to 1000 atmospheres and a temperature within the range of from 25 C. to .150 C., a mixture consisting of sulfur dioxide; tetrafluoroethylene and benzoyl peroxide,

10:1 and" the benzoyl peroxide being present in an amount within the range of from 0.01% to 1% of the sum of the weights of the sulfur dioxide and tetrafluoroethylene.

JESSE mos. ROBERT M. JOYCE, .n.

a sulfur dioxide- 

